Qt QtConcurrent::Run 非阻塞方式调用

一、说明
QFutureWatcher provides information and notifications about a QFuture. Use the setFuture() function to start watching a particular QFuture.
二、代码

#include "widget.h"
#include "ui_widget.h"
#include <QtConcurrent>
#include <QFuture>
#include <QFutureWatcher>
#include <QTimer>
#include <QDateTime>
Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    QFutureWatcher<void> *pwatcher = new QFutureWatcher<void>;
    connect(pwatcher, SIGNAL(finished()),
            this, SLOT(on_finished()));

    QFuture<void> f1 = QtConcurrent::run(hello,QString("demo1"));
    QFuture<void> f2 = QtConcurrent::run([=]{
        hello("demo2");
        //延时
        _sleep(3000);
    });

    pwatcher->setFuture(f2);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::hello(const QString &str)
{
    qDebug()<<"Widget hello"<<str<<"from"<<QThread::currentThread();
}

void Widget::on_finished()
{
    qDebug()<<"Widget QFuture f2 on_finished";
}